[GeoffR]

The main thing to know is that the current-chapter and time remaining progress options only work for KePub books. ePub books always show entire-book progress even if the current-chapter option is selected, and will show page numbers instead of time remaining.

Also, the current chapter progress only works properly if the KePub book has been created to Kobo's guidelines, which means one chapter per internal file.

You can convert ePub books to KePub using the KoboTouchExtended driver in Calibre, but if the book has multiple chapters per file then further work will be needed or else the current-chapter progress will not be accurate.

Note that KePub books have an option to show a lot of other reading stats including a bar chart of the chapter lengths, an estimated time to complete the current and next chapters, as well as the percentage complete of the current chapter. This is shown as a popup so can be used in full screen mode too, but again for this to work properly the book has to be organised as one chapter per internal file.